Tour of a Secret Garden Tucked Away Behind Pink Granite

THERE is a secret garden tucked away behind the walls of the National Gallery of Art. Few visitors see it. It consists of nine greenhouses, ranging from conventional glass to unconventional plastic. And it keeps the exhibits at the gallery flowering all year round.

Visitors to the current ``Matisse in Morocco'' show, for instance, enter through a Moorish arcade surrounded by the pink, orange, and yellow flowering trees known as lantana, as well cypresses, heady jasmine, and oleander from the greenhouses.

The line of greenhouses, which hugs the edge of the pink granite building near its Seventh Street entrance, is stashed away behind a huge double door resembling the gates of a French courtyard. Don Hand, chief horticulturalist, presides over the 13,000 sqauare feet of greenhouses, which keep the exhibitions, restaurants, caf'e areas, and gala celebrations decked in flowers.

Cynthia Burton, a gallery horticulturist, leads a quick tour through the greenhouses where she works. The air smells warm, loamy, and indefinably sweet from the mix of plants thriving there: the lavender agapanthus they are raising - ``hopefully for a party in May''; the sultry sweet gardenia; the tiny, rosy daisies of leptospermum; orange trees; and leggy fuschias. The air is full of scents and petals: the purple sweetness of heliotrope, the piquancy of pineapple sage, the piney smell of rosemary topiary trees.

The greenhouses grow less common plants, as well as perennials and annuals: plumbago, streptocarpus, ixora, serissa foetida. Among the prize flowers, the Ames collection from Boston includes 87 different varieties of azaleas, from white to pink, purple, and peppermint striped, including some originals from China dating back to 1917.

Horiculturist Burton says the first greenhouses were built in 1952 and added to until 1976, when the last three were installed.

Does she have any plant-growing secrets?

Yes. In addition to the usual care and feeding of the plants, ``I play music in here - soft rock.''